Estimation of carbon monoxide



June 23, 1925.

W. YANT ET AL ESTIMATION OF CARBON 'MONOXIDE Filed Nov. 19, 1923 Patented June 23, 1925.

WILLIAM YANT, OF PITTSBURGH, PENNSYLVANIA, ALN'D ROYD R. S-AYERS, OF WASH- INGTON, DISTRICT OF COLUMBIA.

ESTIMATION OF CARBON MONOXIDE.

Application filed November 19, 1923. Serial No. 675,771.

. To all whom it may concern:

Be it known that we, WILLIAM YANT and Born R. SAYERS, citizens of the United States, residents of Pittsburgh, in the county of Allegheny and State of Pennsylvania,

and Washington, District of Columbia, respectively, have invented a new and useful Improvement in the Estimation of Carbon Monoxide; and we do hereby declare the following to be a full, clear, and exact description thereof.

Our invention relates to the estimation of carbon monoxide by quantitatively deter mining carbon monoxide-hemoglobin and oxyhemoglobin in blood, and its general object is to provide a simple and rapid colorimetric method for determining these constituents, which can be conveniently carried out in the laboratory or in the field without the use of bulkyreagents or complicated apparatus, and With little or no computation. This method is suitable for use in diagnosing cases of carbon monoxide poisoning or in connection with research experiments upon men and animals. It is also adapted to be used by field investigators and observers engaged in the work of detecting the presence and quantity of carbon monoxide in air and other gases, as in the inspection of domestic gas-heating appliances, vehicular tunnels, mines and industrial plants.-

Another. object of our invention is to provide a convenient set of portable apparatus for carrying out this method.

Our method of determining carbon monoxide consists, in general terms, in react ing upon a sample of blood containing, or suspected to contain, carbon monoxide, with a reagent capable of destroying the red color of the blood except the red color due to the presence of carbon monoxide-hemoglobin, and comparing the resulting color with a previously prepared series of standard colors corresponding to the colors produced by definite quantities of carbon monoxidehemoglobin in the blood. Another feature of our invention consists in accelerating the color reaction by means of a developer, thus shortening the method and enabling it to be carried out in a few minutes.

Our invention. is based upon the fact that certain reagents, of which tannic acid is typical, when added to blood or a bloodsolution containing carbon monoxide-hemoglobin, produce cloudy suspensions which have a red color, the depth of the color depending upon the amount of carbon monoxide which is combined with the hemoglobin of the blood. In the .absence of carbon monoxide the red color of the blood is destroyed and the suspension has a gray or yellowish-gray color.

This reaction apparently consists in a selective reduction of the hemoglobin compounds in the blood, oxyhemoglobin being reduced and its color destroyed, while carbon monoxide-hemoglobin remains red. This color reaction has-long been known, but no means have heretofore existed for using the reaction in a quantitative way. The value of this reaction in practical use has also been limitedby the fact that the final color is reached only after the mixture of blood and the reagent is allowed to stand for a considerable, period of time, twelve hours or more being required when tannic acid alone is employed as the reagent. Consequently this color reaction has heretofore been practically useless.

We have discovered that the reaction between blood and tannic acid or an equivalent reagent may be accelerated by the use of certain developers, such as pyrogallic. acid, which, when added to a reacting mixture of tannic acid and blood, reduce the time necessary for the reaction from many hours to a few minutes. In addition to pyrogallic acid, a number of other developers are suit-able for this purpose, among which may be mentioned oxalic acid, resorcinol, quinol,'and, in general, any reducing agent which will not destroy the color of carbon monoxide-hemoglobin under the conditions described herein. A somewhat similar effect in accelerating the tannic-acid reaction may be produced by means of heat, but since heat is not always accessibleor convenient, we prefer to make use of a developing reagent such as pyrogallic acid or one of the other substances mentioned above.

For the purpose of comparison with the samples to be examined, it is necessary to prepare a standard series of colors representing the colors produced by definite quantities of carbon monoxide-hemoglobin in the blood, and arranged in a convenient scale. For example, a series of tubes of the same size and shape as the test tubes in which the determinations are to be carried out, may be prepared by filling or internally coating the tubes with opaque pigments of the proper colors. The standards may be prepared from actual blood, but the colors will deteriorate after standing for some time, and we therefore prefer to color the tubes or other standards with permanent pigments. One unit of the standard scale may represent the appearance produced by the tannic acid reaction when carbon monoxide is absent, the next tube may show'the color produced when 10 per cent of the hemoglobin of the blood has been transformed into carbon monoxide-hemoglobin, the next may show the color when 20 per cent has been so transformed, and so on to a maximum of 100 per cent. When the standards are in the form of tubes, they may be mounted on a convenient support to be transported and used, such an arrangement being shown in the accompanying drawing, in which:

Fig. 1 is aperspective view of a set of standard color tubes arranged upon a hinged rack in a suitable case; Fig. 2 is a similar perspective view showing the rack folded down in the case; and Fig. 3 is a perspective view of a holder for a set of instruments which may be carried in the case.'

In the drawing the numeral 2 indicates a rectangular box having a hinged cover 3 and a suitable fastener'4. A rack consisting of a base 5 and a partition 6 is pivotally secured to the bottom of the box 3 by means of hinges 7. On one side of the partition 6 a row of holes are formed in the base 5, and in these holes are set the open ends of a row of small test tubes 8 prepared'in a series of colors in the manner described above. The test tube at the left of Fig. 1 may show the color of the test reaction upon blood which is free from carbon monoxide, and the other test tubes may be arranged in an ascending scale of percentages which may be marked on the partition 6, as shown on Fig. 1.

On the other side of the partition 6, the base 5 may be provided with any convenient, number of holes, and an angle-strip 10 having corresponding openings may be fastened to the partition 6, forming a test tube rack for holding test tubes 11 which are preferably of the same size as the test tubes 8 which formthe color scale. Necessary instruments for taking samples of blood and for diluting the samples may be carried in the space 12 which is formed whentherack is folded down into the box as shown in Fig. 2. l

A convenient method of carrying the instruments as illustrated in Figs. 2 and 3, which show a block 15, of wood or other suitable material, having openings to receive a bottle 16 containing Water, a vial 17 containing reagent material, a blood lancet 18 and a pipette 19 for diluting the samples.

The necessary reagent material, which is suitably a mixture of tannic acid and pyrogallic acid, may be put up in capsules, some of which are shown at 13, each capsule containing a suflicient quantity of the reagent material to react with the samples of blood to be tested. The reagent may ,also be provided in the form of tablets ormay be carried loose in the vial 17. r I

The determination of carbon monoxide may be carried out with undiluted blood, but it is convenient to dilute the blood'with about 20 parts of water. In using this apparatus to determine carbon monoxlde-hemoglobin in blood, a sample of blood, of the same quantity on which the color scale is based, is taken from the patient and is diluted with about 20 parts of water. original sample of-blood may be 0.10 c. c. which is diluted to 2.0 c. c. This solution is placed inone of the test tubes 11, and to this is added the contents of one of the capsules 13 or an equivalent amount of reagent in other form. For a blood sample of 0.10 c. c., a suitable quantity of reagent material is about 0.04 gram of a mixture of equal parts of tannic acid and pyrogallic acid. These proportions may vary considerably although too great an excess of the reagent is to be avoided. The mixture is shaken and allowed to stand for eight or ten minutes, and the test tube is then compared with the series of standard color tubes 8. By finding the standard tube which it most nearly matches in color, the percentage of carbon monoxide-hemoglobin in the original blood is shown .directly.

If desired, the reagent material may be prepared in solution before being used. In that case the reagent material may be dissolved in water, in the proportion of about 0.04 gram of reagent per 0. c. of water, and the samples of blood may then be diluted in the proportion of 0.10. c. of blood to 1 c. c. of water, and 1 c. c. of the reagent solution is added. This method is convenient when a considerable number of determinations are'to be made at about the same time. a

The standard color scale need not be composed of coloredtest tubes, but-ma be prepared in various other forms trips or spots of the proper colors may be rinted or painted on paper or other suitab e surface. For convenient comparison, such spots may be shaped to correspond to the test tubes or other containers in which the reaction is to be'performed, or they may be arranged to be compared with filter paper saturated with the reaction products.

The same general method may be employed in determining carbon monoxide in air or other gases. A standard blood solution of the proper strength is prepared in the manner described above and is shaken The with a definite quantity of the gas to be analyzed for carbon monoxide until equilibrium is produced between the carbon monoxide-hemoglobin and the oxyhemoglobin in the blood. The blood is transferred to a test tube, the reagent material is added,

as above, and the color so produced is compared with the standard color scale. This gives the quantity of carbon monoxidehemoglobin in the blood, and from this quantity the percentage of carbon monoxide in the original gas is readily calculated.

The determination of carbon monoxidehemoglobin, in the manner described above, also gives a direct indication of the amount of oxyhemoglobin in the blood, the normal quantity of oxyhemoglobin being taken as 100%. The percentage of carbon monoxidehemoglobin is read on the color scale, and the difference between this percentage and 100% gives the percentage of unchanged oxyhemoglobin in the blood sample.

Itwill be understood that our invention is not limited to the exact materials, quantities or details of construction herein shown and described, and that our invention includes the use of any reagents, apparatiis or operations which fall within the scope of the appended claims.

We claim as our invention:

1. The method of quantitatively estimat ing carbon monoxide, that comprises treating a known quantity of blood with a reagent capable of destroying the red color of oxyhemoglobin, while leaving the red color of carbon monoxide-hemoglobin, and comparing the resulting color with a standard colorimetric scale prepared in colors corresponding to definite quantities of carbon monoxide-hemoglobin in the said quantity of blood.

2. The method of quantitatively estimating carbon monoxide that comprises treating a known quantity of blood with a reagent capable of destroying the red color of oxyhemoglobin, while leaving thered color of carbon mopoxide-hemoglobin, accelerating the said reaction, and comparing the resulting color with a standard colorimetric scale prepared in colors corresponding to definite quantities of carbon monoxide hemoglobin in the saidquantity of blood.

3. The method of quantitatively estimating carbon monoxide that comprises reacting upon a known quantity of blood with tannic acid, acceleratin the said reaction,'and comparing'the resu ting color with a standard colorimetric scale prepared in colors corresponding to definite quantities of carbon monoxide-hemoglobin in said quantity of blood.

4. The method of quantitatively estimating carbon monoxide that comprises treating a known quantity of blood with tannic acid and an accelerating reagent, and comparing the resulting color with a standard colorimetric scale prepared in colors corresponding to definite quantities of carbon monoxide-hemoglobin in the said quantity of blood.

5. The method of quantitatively estimating carbon monoxide that comprises treating a known quantity of blood with tannic acid and pyrogallic acid, and comparing the resulting color with a standard colorimetric scale prepared in colors corresponding to definite quantities of carbon monoxidehemoglobin in the said quantity of blood.

6. The method of quantitatively estimating carbon monoxide that comprises mixing about one part of blood with about 20 parts of water and about 4 parts of reagent material consisting of equal parts of tannic acid and an accelerating reagent, allowing the mixture to react until a stable color is produced, and comparing the resulting color with a standard colorimetric scale prepared ing color with a standard-colorimetric scale prepared in colors corresponding to definitequantities of carbon monoxide-hemoglobin in the said quantity of blood.

8. The method of quantitatively estimating carbon monoxide that comprises diluting a known quantity of blood, agitating the blood solution with a medium containing, or suspected to contain, carbon monoxide until equilibrium is established between the oxyhemoglobin and carbon monoxide-hemoglobin present, treating the solution with tannic acid and an accelerating reagent, and comparing the resulting color with a standard colorimetric scale prepared in colors corresponding to definite quantities of carbon monoxide-hemoglobin in the said quantity of blood.

9. The method of quantitatively estimating carbon monoxide, that comprises treating a known quantity of blood with a coagulating agent, and comparing the resulting color with a colorimetric scale corre duced by reaction of tannic acid reagent carbon monoxide-hemoglobin, other similar with blood containing definite quantities of test tubes for containing samples, and cap- 10 carbon monoxide hemoglobin. Sules containing reagent material.

11. Apparatus for estimating carbon mon- In testimony whereof we, the said WIL- 5 oxide comprising a series of test tubes inter- LIAM YANT and BOYD SAYERS, have here nally colored to represent the colors pro- Unto Set 0111 handsduced by reaction of tannic acid reagent WILLIAM YANT, With blood containing definite quantities of ROYD R. SAYERS. 

